Tail-valve apparatus for compressed-air brakes



II. DUBOIS.

TAIL VALVE APPARATUS FOR COMPRESSED AIR BRAKES.

APPLICATION FILED FEB. 24, 1920.

Patented Jan. 17, 1922 /I i ze In R. DUBOIS.

TAIL VALVE APPARATUS FOR CDMPRESSED AIR BRAKES.

APPLICATION FILEU FEB.24. 1920. 1 ,404,102. Patented Jan. 17, 1922.

4 2 SHEETS-SHEET 2. l

t 3g v 55 l 30 7 UNITED STATES PATENT OFFICE.

ROBERT DUBOIS, OF PARIS, FRANCE.

Specification of Letters Patent.

Patented Jan. 17, 1922.

Application led February 24, 1920. Serial No. 360,727.

(GRANTED UNDER THE rnovrsroNs or THE Aer or MARCH 3, 1921, 41 STAT. L., 1313.)

To all 'whom it. may concern: d Be it known that I, ROBERT DUors,a cit-i,-A zen of the French Republic, residing lat No. 6 Rue Gounod, Paris, France, have invented certain new and .useful Improvements in rFail-Valve Apparatus for Compressed-Air Brakes, (for which I have filed ap lication in France, MayV 28, .1914, Patent o. 472,- 766,) 0f lWhichthe following is arspecication. v

Valves for compressed air brakes have already been constructed which assure an immediate locking of the brakes in ease kof the accidental fall of pressure in the Vmain .or

auxiliary compressed air reservoirs. .In

these devices which comprise a valve subject on one of its faces totheaction of compressed air, the other face to the actiono a spring, the movement of the valve under the action of the spring when the pressure of the compressed air falls below a certain value causes the openingof a discharge oritice, the result of which is a sudden drop in pressure, the continuation of the movement of the valve then being capable of closing the discharge oriicewhen the pressure` has fallen below another value. In the present invention which permits accessorily of at.- taining the same results` as devices of this type and under better conditions,` itis proposed that the driver, by testing the brakes, assure himself that there is no break in the continuit of the conduit over the entire length o the train. f

For Vthis purpose three conditions are necessary. l

l. That the valve be itted on the general passage itselfl and not on the reservoir.r In fact, in this latter case, the fall of pressure produced in the conduit causing. `the triple valve to operate will isolate the reservoir which -will divert, a portion ofits air into the brake cylinder. Hence, starting from the moment of this fall of pressure in the reservoir there wi-llbe no certainty as tothe fall of pressure Vin the conduit. Y f.

2. Tha-t the operation ofthe valve produce iu the general conduit a drop in pressure which is exact between two limits. To obtain this result use is not made et devices as crude as those mentioned above. In these valves, in fact,the discharge orifice opened wide for the discharge of the compressed air, is suddenly andl `completely closed as soon asl the local pressure in its vicinity is below a determined limit. In the valve forming the subject or" the present invention, on the contrary, the discharge port is closed progressively, the pressure thus having time to be equalized over the entire conduit and the complete closure being effected. only when equilibrium isestablished. f

. 3. That the valve be iitted at the rear of the train so as to indicate the continuity ot the conduit over its entire length.y For this purpose the construction of the valve which isthe subject of the invention is such that. it can be applied only to the end of the train.

A constructional form of this invention is illustrated by way of example in the accompanying' drawings in which:A

Fig. l is a longitudinal section of the iniproved valve apparatus when fitted in place on the rear coupling hook of the tail vehicle of the train.

Fig. 2 is asection on the line 2 2 of Fig. l and Fig. 3 is an underside view of the air-discharge slide.

Fig. 4 is a partial longitudinal section ot Va modified form of the means of mounting the valve apparatus; and s Fig. 5 is a section through the support shown in Fig. 4.

The improved valve apparatus is in direct .communication with the compressed air train pipe by way of the union l (Fig. 2) provided with a coupling not shown.

The discharge outlet of the air is controlledby a valve 2 and the slide 3 (this latter is shown separately in Fig. 3).

The valve 2 is actuated by a lever 4 fnlcrumed on a pin 5 inside a box G formed by two sides 7 and atop 8. This box 6 serves for the suspension of the apparatus and is placed upon the back coupling hook 9 ot the train.

So long as the improved apparatus is not mounted on the coupling hook, the lever 4 is pressed back by the spring il of the valve 2, and it occupies the position indicated in dotted lines at l0 in Fig. l; the valve 2 is closed. On the contrary, when the improved apparatus is mounted on a coupling hoek the lever 4 presses back the valve and the latter remains ofi' its seat.

The slide 3 is capable of sliding vertically in a chamber 40; its motion is produced by means of a guide member 12, by the counterspring 13 on the one hand, and by an escape ment finger 14 on the other hand.

This finger 14isprovided with a small operating arm 15 and is carried by a piston A16 adapted to move in a cylindrical chamber 41. Thefinger' 14 which is capableoi' turning on the pivot pin 17, is constantly held in the position shown in Fig. 1by the spring 18 whichpresses againstl the arm 15, and by Vitslieel42 which bears upon a projection43 ofth'epi'ston 16. In Y'thispo'sition' the finger 1 4acts upon the tail 19 of thelguide member 12. The escapement c omes into action l5,

whfenfthe arm 15 strikes against the top 20 of the 4chamberv '41.

, heir-tight piston 16 is enposed'on its upper tace tov the air pressure in the train pipe, kand onits lowerface tothe action of ,itwofsprings 21 and 22 jthrough the medium of sliding sleeves 23 and 24. These springs With their sleeves are arranged in abox 44 lit-ted with a lid 25.

When the piston 16 is at the bottom of its stroke, it is subjected to the action of the two springs. lhen it has moved'through a certain portionbfits stroke, the y'sleeve 23 strikes against the lid 25, and the piston is acted vvupon "atY its lower face only byV the spring 22.

The sli-de'm3 has an aperture 26 V with anV the tail valve apparatus upon thecoupl'ing l,hoolnis extremely simple, but it may have drawbacks, and4 especially in the ycase, fof automatic couplings, it may render the apparatus'liable to be damaged if a collision shouldl'occurat the tail of the train.

In the moditied fform -illustrated Y inYA Figs. 4 and 5, the valve apparatus is mounted on a support '30 which is xedto the vehicleV 31 and which comprises essentially a cock plug ,'32 pierced throughout with a hole 33. This plugV isfadapted'to rotate lon its axis or to move longitudinally. On the other hand, the support comprises above andbelow the ,plug 32 two holes 34 and 35, situated'ex'actly opposite each other and having the same cross `Section as-the hole 33.` In a determined position of the plug'32 they can coincidewith the intermediate hole 33.v In Fig. 4, the holes 33, 34 and 35 are shown in line with one another, whereas the contrary is shown in Fig. 5.

The support 30 has moreoveryon the side `farthest from the vehicle, a projection 36 which, when the tail valve apparatus is mounted in position (Figf4), adapted to meetand raise the Stem 39 for actuating the test valve 2.

Thel tail valve, apparatusris provided with ay shank' 37 which is adapte'd to enter the holes33, 34 and 35 when all these holes coincide'"togetherJ and it is also'Y provided `with acavity 38 into V- which the projection 36 can enter.

'Ihe" lplug 32:"'is operatively connected by a suitable device to the automatic coupling in such a manner that thefhole 33`is situated opposite the hles 34 and 35 only when lthe iuatuatng"memberv of thefcoupling is iny "osition' corres ondino to ."o en runcoupled),"coiiplirigfV The"coupling idevi'ce may be"fo'rmed, for eiirai'nple, by a Vlever40 to which thelkey'32 is rigidly attached, this Y Y' lever y40 heingrpivoted fto'rfanother' lever which `is""co`nne'cted to the "draft device. Consequently the ktestvalve can be lifted (opened) only when "thecoupling isit'sel open and the tailvalve apparatus can operate only vvhenjit is mounted on the last vehicle ofthe train. n

.Itis to be understood thatfthe 'arrangemeint of a plug pierced with; a Vhole 'and operatively y' connected tothe coupling apparatus is given solelyvvbyway o'f'ex'ainple; it may be replaced bylany"otherfarrange ment wherein anym'ember, vin fjoperati've connection with the coupling, will "be" able, when coupling: is possible, tov enter' the structure of the tail valve apparatus V'which is assumedtovbe mounted on its supportand will jbe situated'outside the' said structure when 'coupling is impossible.

To facilitate the'jdescription ofthe working of the improved apparatus it is assumed that the normal'working "pressure in the' train'pipe is'5 kg., 'and that the tail valve ,ishso regulatedas 'to causea discharge or the airbetween the'limits'of3fkg. and 1kg.

rIhe r'uar'gin' between 5 'lrgl' and ,3 kg. 'is suiiicient to allow p of applying the gbralres normally without vcausing the' tail lvalve to come intovaction. I I n v" 4, f

' Solong'as the pressu'rejin the train pipe is higherthan 3 kg., nthe various fpa'rts'will occupy the positions 'shown in' Figs. 1 to 4. Y,Valve ,2 is openowing to the improvedl apparatusbeing mounted, and' the aperture 27 fisclosed by the' slide 3 because 'the air pressure is capable of counterbalancing the acvtion Yof springs 2,1 and 22.

Vhen the vpressure in the trainY pipe 1falls to 3 kg., the Vpistonjisraised bythe' 'two springs 21 and '22; .the aperture 26 inthe slide comes opposite theaperture27 Yof the chamber 40, and the air is dischargedV into the atmosphere. The sleeve23 now bears against the Acover 25.

The lslide 3 remainjsin'l this position ,until 'the pre'ssurehas fallen to about 1kg., vso that it no longer counterbal'ances completely' the IVIO action of the spring 22 which alone pushes the piston upwards.

From this moment the piston continues to move under the action ot the spring 22; the discharge aperture 27 is partl closed; and at the same time the arm 15 of the finger 14 strikes against the wall 20; the finger rocks and releases the t-ail 19; the slide is no longer acted upon except by the spring 13 and it returns into its original position shown in F ig. 1, and the discharge of the air ceases. The notch 28 formed in the slide is intended to prevent'the aperture from being completely closed before the escapement is operating with certainty.

From this moment it is necessary to reestablish in the train pipe a higher pressure than 3 kg. in order that the piston shall resume its original position and the escapement become re-set.

To test the brakes, the driver, after having charged the train pipe. with a pressure approximating to the normal pressure, applies the brakes slightly in order to disconnect the pipe of the auxiliary reservoirs, and then he allows the pressure to fall slowly. If there is no break in the train pipe as far as the tail valve, the pressure on rising to 3 kg. will fall suddenl Y to 1 kg.

When a consi erable fall in pressure occurs so as to put the brakes hard on, this fall will be increased by the operation of the tail valve.

In the case of a slow fall in the pressure, the brakes will bey put hard on when the pressure reaches the limit prescribed for the o-perationof the tail valve.

What I claim is 1'. In a tail valve apparatus for compressed air brakes, in combination, a piston subjected on one face to the air pressure,

two springs of different strength acting on the' other face of the piston, an air discharge valve, an air outlet, a slide adapted to move by said air outlet and provided with an aperture and with a notch leading from the aperture and forming an extension thereof, and an escapement mechanism connected to said piston for causing the movements of said slide.

2. In a tail valve apparatus ifor compressed air brakes, in combination, a piston subjected on one face to the air pressure, two springs of different strength acting on the other face of the piston, an air discharge valve, an air outlet orifice, a slide adapted to move pastsaid orifice and provided with an aperture and with a notch leading from the aperture and forming an extension thereof, an escapement mechanism connected to the piston for causing the movements of slide, a member attached to the vehicle for the mounting of the valve apparatus, and a coupling hook in operative relation with said member.

3. In a tail valve apparatus for compressed air brakes, in combination, a piston subjected on one face to the air pressure, two springs of different strength acting on the other face of the piston, anair discharge valve, an air outlet orifice, a slide adapte'd to move past said orifice and provided with an aperture and with a notch leading froml the aperture and forming an extension thereof, an escapement mechanism connected to said piston for causing the movements of said slide', a member attachedto the vehicle for the mounting of the valve apparatus, a coupling hook in operative relation with said member, and means controlled by said member for acting upon the air discharging valve whereby said valve is open when the Y valve apparatus is mounted in position.

In testimony whereof I have signed my name to this specification.

ROBERT DUBOIS. 

